package utils;

/*

   Porter stemmer in Java. The original paper is in

       Porter, 1980, An algorithm for suffix stripping, Program, Vol. 14,
       no. 3, pp 130-137,

   See also http://www.tartarus.org/~martin/PorterStemmer

   History:

   Release 1

   Bug 1 (reported by Gonzalo Parra 16/10/99) fixed as marked below.
   The words 'aed', 'eed', 'oed' leave k at 'a' for step 3, and b[k-1]
   is then out outside the bounds of b.

   Release 2

   Similarly,

   Bug 2 (reported by Steve Dyrdahl 22/2/00) fixed as marked below.
   'ion' by itself leaves j = -1 in the test for 'ion' in step 5, and
   b[j] is then outside the bounds of b.

   Release 3

   Considerably revised 4/9/00 in the light of many helpful suggestions
   from Brian Goetz of Quiotix Corporation (brian@quiotix.com).

   Release 4

 */

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;

/**
 * Stemmer, implementing the Porter Stemming Algorithm
 * 
 * The Stemmer class transforms a word into its root form. The input word can be
 * provided a character at time (by calling add()), or at once by calling one of
 * the various stem(something) methods.
 */

public class Stemmer implements IStemmer {
   private char[] b;
   private int i, /* offset into b */
   i_end, /* offset to end of stemmed word */
   j, k;
   private static final int INC = 50;
   
   /* unit of size whereby b is increased */
   public Stemmer() {
      b = new char[INC];
      i = 0;
      i_end = 0;
   }
   
   /**
    * Add a character to the word being stemmed. When you are finished adding
    * characters, you can call stem(void) to stem the word.
    */
   
   public void add(final char ch) {
      if (i == b.length) {
         final char[] new_b = new char[i + INC];
         for (int c = 0; c < i; c++) {
            new_b[c] = b[c];
         }
         b = new_b;
      }
      b[i++] = ch;
   }
   
   /**
    * Adds wLen characters to the word being stemmed contained in a portion of a
    * char[] array. This is like repeated calls of add(char ch), but faster.
    */
   
   public void add(final char[] w, final int wLen) {
      if (i + wLen >= b.length) {
         final char[] new_b = new char[i + wLen + INC];
         for (int c = 0; c < i; c++) {
            new_b[c] = b[c];
         }
         b = new_b;
      }
      for (int c = 0; c < wLen; c++) {
         b[i++] = w[c];
      }
   }
   
   /**
    * After a word has been stemmed, it can be retrieved by toString(), or a
    * reference to the internal buffer can be retrieved by getResultBuffer and
    * getResultLength (which is generally more efficient.)
    */
   @Override
   public String toString() {
      return new String(b, 0, i_end);
   }
   
   /**
    * Returns the length of the word resulting from the stemming process.
    */
   public int getResultLength() {
      return i_end;
   }
   
   /**
    * Returns a reference to a character buffer containing the results of the
    * stemming process. You also need to consult getResultLength() to determine
    * the length of the result.
    */
   public char[] getResultBuffer() {
      return b;
   }
   
   /* cons(i) is true <=> b[i] is a consonant. */
   
   private final boolean cons(final int i) {
      switch (b[i]) {
         case 'a':
         case 'e':
         case 'i':
         case 'o':
         case 'u':
            return false;
         case 'y':
            return i == 0 ? true : !cons(i - 1);
         default:
            return true;
      }
   }
   
   /*
    * m() measures the number of consonant sequences between 0 and j. if c is a
    * consonant sequence and v a vowel sequence, and <..> indicates arbitrary
    * presence,
    * 
    * <c><v> gives 0 <c>vc<v> gives 1 <c>vcvc<v> gives 2 <c>vcvcvc<v> gives 3
    * ....
    */
   
   private final int m() {
      int n = 0;
      int i = 0;
      while (true) {
         if (i > j) {
            return n;
         }
         if (!cons(i)) {
            break;
         }
         i++;
      }
      i++;
      while (true) {
         while (true) {
            if (i > j) {
               return n;
            }
            if (cons(i)) {
               break;
            }
            i++;
         }
         i++;
         n++;
         while (true) {
            if (i > j) {
               return n;
            }
            if (!cons(i)) {
               break;
            }
            i++;
         }
         i++;
      }
   }
   
   /* vowelinstem() is true <=> 0,...j contains a vowel */
   
   private final boolean vowelinstem() {
      int i;
      for (i = 0; i <= j; i++) {
         if (!cons(i)) {
            return true;
         }
      }
      return false;
   }
   
   /* doublec(j) is true <=> j,(j-1) contain a double consonant. */
   
   private final boolean doublec(final int j) {
      if (j < 1) {
         return false;
      }
      if (b[j] != b[j - 1]) {
         return false;
      }
      return cons(j);
   }
   
   /*
    * cvc(i) is true <=> i-2,i-1,i has the form consonant - vowel - consonant
    * and also if the second c is not w,x or y. this is used when trying to
    * restore an e at the end of a short word. e.g.
    * 
    * cav(e), lov(e), hop(e), crim(e), but snow, box, tray.
    */
   
   private final boolean cvc(final int i) {
      if (i < 2 || !cons(i) || cons(i - 1) || !cons(i - 2)) {
         return false;
      }
      {
         final int ch = b[i];
         if (ch == 'w' || ch == 'x' || ch == 'y') {
            return false;
         }
      }
      return true;
   }
   
   private final boolean ends(final String s) {
      final int l = s.length();
      final int o = k - l + 1;
      if (o < 0) {
         return false;
      }
      for (int i = 0; i < l; i++) {
         if (b[o + i] != s.charAt(i)) {
            return false;
         }
      }
      j = k - l;
      return true;
   }
   
   /*
    * setto(s) sets (j+1),...k to the characters in the string s, readjusting k.
    */
   
   private final void setto(final String s) {
      final int l = s.length();
      final int o = j + 1;
      for (int i = 0; i < l; i++) {
         b[o + i] = s.charAt(i);
      }
      k = j + l;
   }
   
   /* r(s) is used further down. */
   
   private final void r(final String s) {
      if (m() > 0) {
         setto(s);
      }
   }
   
   /*
    * step1() gets rid of plurals and -ed or -ing. e.g.
    * 
    * caresses -> caress ponies -> poni ties -> ti caress -> caress cats -> cat
    * 
    * feed -> feed agreed -> agree disabled -> disable
    * 
    * matting -> mat mating -> mate meeting -> meet milling -> mill messing ->
    * mess
    * 
    * meetings -> meet
    */
   
   private final void step1() {
      if (b[k] == 's') {
         if (ends("sses")) {
            k -= 2;
         }
         else if (ends("ies")) {
            setto("i");
         }
         else if (b[k - 1] != 's') {
            k--;
         }
      }
      if (ends("eed")) {
         if (m() > 0) {
            k--;
         }
      }
      else if ((ends("ed") || ends("ing")) && vowelinstem()) {
         k = j;
         if (ends("at")) {
            setto("ate");
         }
         else if (ends("bl")) {
            setto("ble");
         }
         else if (ends("iz")) {
            setto("ize");
         }
         else if (doublec(k)) {
            k--;
            {
               final int ch = b[k];
               if (ch == 'l' || ch == 's' || ch == 'z') {
                  k++;
               }
            }
         }
         else if (m() == 1 && cvc(k)) {
            setto("e");
         }
      }
   }
   
   /* step2() turns terminal y to i when there is another vowel in the stem. */
   
   private final void step2() {
      if (ends("y") && vowelinstem()) {
         b[k] = 'i';
      }
   }
   
   /*
    * step3() maps double suffices to single ones. so -ization ( = -ize plus
    * -ation) maps to -ize etc. note that the string before the suffix must give
    * m() > 0.
    */
   
   private final void step3() {
      if (k == 0) {
         return; /* For Bug 1 */
      }
      switch (b[k - 1]) {
         case 'a':
            if (ends("ational")) {
               r("ate");
               break;
            }
            if (ends("tional")) {
               r("tion");
               break;
            }
            break;
         case 'c':
            if (ends("enci")) {
               r("ence");
               break;
            }
            if (ends("anci")) {
               r("ance");
               break;
            }
            break;
         case 'e':
            if (ends("izer")) {
               r("ize");
               break;
            }
            break;
         case 'l':
            if (ends("bli")) {
               r("ble");
               break;
            }
            if (ends("alli")) {
               r("al");
               break;
            }
            if (ends("entli")) {
               r("ent");
               break;
            }
            if (ends("eli")) {
               r("e");
               break;
            }
            if (ends("ousli")) {
               r("ous");
               break;
            }
            break;
         case 'o':
            if (ends("ization")) {
               r("ize");
               break;
            }
            if (ends("ation")) {
               r("ate");
               break;
            }
            if (ends("ator")) {
               r("ate");
               break;
            }
            break;
         case 's':
            if (ends("alism")) {
               r("al");
               break;
            }
            if (ends("iveness")) {
               r("ive");
               break;
            }
            if (ends("fulness")) {
               r("ful");
               break;
            }
            if (ends("ousness")) {
               r("ous");
               break;
            }
            break;
         case 't':
            if (ends("aliti")) {
               r("al");
               break;
            }
            if (ends("iviti")) {
               r("ive");
               break;
            }
            if (ends("biliti")) {
               r("ble");
               break;
            }
            break;
         case 'g':
            if (ends("logi")) {
               r("log");
               break;
            }
      }
   }
   
   /* step4() deals with -ic-, -full, -ness etc. similar strategy to step3. */
   
   private final void step4() {
      switch (b[k]) {
         case 'e':
            if (ends("icate")) {
               r("ic");
               break;
            }
            if (ends("ative")) {
               r("");
               break;
            }
            if (ends("alize")) {
               r("al");
               break;
            }
            break;
         case 'i':
            if (ends("iciti")) {
               r("ic");
               break;
            }
            break;
         case 'l':
            if (ends("ical")) {
               r("ic");
               break;
            }
            if (ends("ful")) {
               r("");
               break;
            }
            break;
         case 's':
            if (ends("ness")) {
               r("");
               break;
            }
            break;
      }
   }
   
   /* step5() takes off -ant, -ence etc., in context <c>vcvc<v>. */
   
   private final void step5() {
      if (k == 0) {
         return; /* for Bug 1 */
      }
      switch (b[k - 1]) {
         case 'a':
            if (ends("al")) {
               break;
            }
            return;
         case 'c':
            if (ends("ance")) {
               break;
            }
            if (ends("ence")) {
               break;
            }
            return;
         case 'e':
            if (ends("er")) {
               break;
            }
            return;
         case 'i':
            if (ends("ic")) {
               break;
            }
            return;
         case 'l':
            if (ends("able")) {
               break;
            }
            if (ends("ible")) {
               break;
            }
            return;
         case 'n':
            if (ends("ant")) {
               break;
            }
            if (ends("ement")) {
               break;
            }
            if (ends("ment")) {
               break;
            }
            /* element etc. not stripped before the m */
            if (ends("ent")) {
               break;
            }
            return;
         case 'o':
            if (ends("ion") && j >= 0 && (b[j] == 's' || b[j] == 't')) {
               break;
            }
            /* j >= 0 fixes Bug 2 */
            if (ends("ou")) {
               break;
            }
            return;
            /* takes care of -ous */
         case 's':
            if (ends("ism")) {
               break;
            }
            return;
         case 't':
            if (ends("ate")) {
               break;
            }
            if (ends("iti")) {
               break;
            }
            return;
         case 'u':
            if (ends("ous")) {
               break;
            }
            return;
         case 'v':
            if (ends("ive")) {
               break;
            }
            return;
         case 'z':
            if (ends("ize")) {
               break;
            }
            return;
         default:
            return;
      }
      if (m() > 1) {
         k = j;
      }
   }
   
   /* step6() removes a final -e if m() > 1. */
   
   private final void step6() {
      j = k;
      if (b[k] == 'e') {
         final int a = m();
         if (a > 1 || a == 1 && !cvc(k - 1)) {
            k--;
         }
      }
      if (b[k] == 'l' && doublec(k) && m() > 1) {
         k--;
      }
   }
   
   /**
    * Stem the word placed into the Stemmer buffer through calls to add().
    * Returns true if the stemming process resulted in a word different from the
    * input. You can retrieve the result with
    * getResultLength()/getResultBuffer() or toString().
    */
   public void stem() {
      k = i - 1;
      if (k > 1) {
         step1();
         step2();
         step3();
         step4();
         step5();
         step6();
      }
      i_end = k + 1;
      i = 0;
   }
   
   /**
    * Test program for demonstrating the Stemmer. It reads text from a a list of
    * files, stems each word, and writes the result to standard output. Note
    * that the word stemmed is expected to be in lower case: forcing lower case
    * must be done outside the Stemmer class. Usage: Stemmer file-name file-name
    * ...
    */
   public static void main(final String[] args) {
      final char[] w = new char[501];
      final Stemmer s = new Stemmer();
      for (final String arg : args) {
         try {
            final FileInputStream in = new FileInputStream(arg);
            
            try {
               while (true)
               
               {
                  int ch = in.read();
                  if (Character.isLetter((char) ch)) {
                     int j = 0;
                     while (true) {
                        ch = Character.toLowerCase((char) ch);
                        w[j] = (char) ch;
                        if (j < 500) {
                           j++;
                        }
                        ch = in.read();
                        if (!Character.isLetter((char) ch)) {
                           /* to test add(char ch) */
                           for (int c = 0; c < j; c++) {
                              s.add(w[c]);
                           }
                           
                           /* or, to test add(char[] w, int j) */
                           /* s.add(w, j); */
                           
                           s.stem();
                           {
                              String u;
                              
                              /* and now, to test toString() : */
                              u = s.toString();
                              
                              /* to test getResultBuffer(), getResultLength() : */
                              /*
                               * u = new String(s.getResultBuffer(), 0,
                               * s.getResultLength());
                               */
                              
                              System.out.print(u);
                           }
                           break;
                        }
                     }
                  }
                  if (ch < 0) {
                     break;
                  }
                  System.out.print((char) ch);
               }
            }
            catch (final IOException e) {
               System.out.println("error reading " + arg);
               break;
            }
         }
         catch (final FileNotFoundException e) {
            System.out.println("file " + arg + " not found");
            break;
         }
      }
   }
   
   @Override
   public String stemWord(String word) {
      
      final Stemmer stem = new Stemmer();
      final char t[] = word.toCharArray();
      stem.add(t, t.length);
      stem.stem();
      word = stem.toString();
      
      return word;
   }
}